Three-Dimensional Simulation of Flow Over Sharp-Crested Weirs Using Volume of Fluid Method

In sharp crested weirs, significant changes occur in the hydraulic characteristics of the flow past the weirs with different geometry. A detailed investigation and better understanding of hydraulic behavior will help practically to choose an appropriate geometry for weir. The purpose of this research is simulate the flow over sharp crested weir and investigate the effect of geometric shapes of sharp crested weirs on hydraulic characteristics of the flow such as pressure, velocity, water level profiles and discharge coefficients. Thus the limitation and usage range of sharp crested weirs are clarified. In this research OpenFOAM open source 3D software with RNG K-ε turbulence model and Volume of Fluid method (VOF) was used to analyze the hydraulic flow passing through sharp crested weir. The correlation coefficient for flow Surface profiles and discharge coefficients among numerical and experimental data is obtained 0.96 for different discharge rates. In the present research, discharge coefficients for rectangular weirs with compression coefficient 0%, trapezoidal and triangular weirs are determined 1.20, 0.68 and 0.51 respectively using discharge rate of 0.05183m³/s. The maximum discharge coefficient is obtained for rectangular sharp crested weir while the triangular sharp crested weir has minimum discharge coefficient.